1. Make sure MainStage is up to date

Make sure you're using the latest version of MainStage 3. Choose Apple menu () > App Store, then click Updates in the toolbar. If an update is available, click the Update button to download and install it.

2. Check device or software compatibility

If you're using an external audio interface, MIDI interface, storage system, or plug-in not made by Apple, make sure it's compatible with the latest version of MainStage 3. Contact the manufacturer for support. If an update is available, follow the manufacturer's instructions to update the device or software.

3. Check documentation

Check MainStage 3 Help to make sure MainStage is working as expected. You can search help for key terms shown in alerts or error messages.

4. Test using built-in audio

Sometimes an incompatible or malfunctioning external audio interface can cause issues with MainStage. If you're using an external audio interface, try using the built-in audio on your Mac instead of the interface.

5. Create a new concert

Choose the devices you want to use for audio input and output from the Audio Input and Audio Output pop-up menus in the dialog.

Click an instrument category on the left, then select the template you want to use.

Click Choose.

Test to see if the issue occurs in the new concert. If the issue doesn't occur in the new concert, the concert you're having issues with might be damaged. You can try to rebuild the concert file.

Rebuild a damaged concert file

When you rebuild a concert, you export the layout, sets, and patches from your concert, then import them into a new concert.

Open the concert you're having issues with.

To export your layout, click Layout, click the gear icon at the top of the Layout section, then choose Export Layout from the menu. Choose a location in which to save the layout, then click Export.

To export your sets and patches, click Edit, click in the Patch List, then press Command–A (or choose Edit > Select All) to select all sets and patches in the Patch List. Drag them to the desktop or a folder.

6. Try a different user account

7. Reset preferences

Resetting MainStage preferences doesn't affect your project files, presets, or patches. However, you do lose any custom preference settings you might have made.

Before resetting preferences, choose MainStage > Preferences and note any specific settings you've made. That way, after resetting preferences, you can go back and reapply your custom settings. For information on different preferences, see Preferences overview in MainStage Help.

To reset your MainStage preferences:

Quit MainStage if it's open.

In the Finder, hold the Option key, then choose Go > Library.

Remove the com.apple.mainstage3.plist file from the Preferences folder.

Restart your Mac.

After your Mac restarts, open MainStage and try to reproduce the issue you were experiencing. If the issue no longer occurs, open MainStage preferences and reapply your custom settings.

8. Reinstall MainStage

If the issue persists, remove and reinstall MainStage. Your existing MainStage concerts won't be deleted, and can be opened after reinstallation.

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